Tube cleaning pellet gun



Oct. 6, 1970 K. HURST 3,531,813

TUBE CLEANING PELLET GUN Filed Sent. 17, 1968 5 SheetsSheet 1 I NVENTOR.KENNE TH H0257 A TTOENE Y Oct. 6, 1970 K. HURST 3,531,813

TUBE CLEANING PELLET GUN Filed Sent. 17, 1968 I .3 Sheets-Sheet 2 FIG'ZI NVENTOR. KEN/V6734 HUZS 7 AT TOENE Y Oct. 6, 1970 K. HURST TUBECLEANING PELLET GUN 5 Sheets-Sheet 5 Filed Sent. 17, 1968 INVENTOR.KENNETH HUEST BY Z A TTOENE Y United States atent Patented Oct. 6, 1970US. Cl. l5104.06 6 Claims ABSTRACT OF THE DISCLOSURE A manuallymanipulatable, magazine fed, pneumatically operated device forpropelling a pellet through a tube of a heat exchanger for the purposeof cleaning the interior of the tube. The device incorporates a manuallyoperated pellet positioning ram operable within the barrel to assist inpassing the pellet from the barrel to the tube and also operative toseal the tube against reverse flow of motive fluid.

BACKGROUND OF THE INVENTION In the manufacture of heat exchangers,especially those of the shell and tube type wherein the interior of theshell houses a plurality of tubes whose ends are mounted to a tube sheetthat closes the end of the shell, it is necessary that one of the finalstages of the fabrication process include that of cleaning the interiorof the assembled tubes. This need arises from the fact that during thevarious steps of the fabrication process the deposition of dirt, metalchips and other sediment in the tubes is inescapable. Moreover, prior tocompletion of the assembly, it must be heat treated which results in thegeneration of metal oxides within the tubes. To remove these oxides, thetubes are subjected to acid pickling and thereafter it is necessary toclean the tubes to insure that no acid residue remains in the tubes uponcompletion of the pickling step since the presence of such acid wouldultimately result in contamination of the fluid passed through the tubesduring operation of the heat exchanger.

In the past, it has been the practice to clean the tubes of such heatexchangers by manually drawing a swab attached to a wire or the likethrough the tube. This is both a laborious and time consuming procedureespecially when it is considered that it is not uncommon for heatexchangers of this type to include thousands of tubes. The presentinvention, therefore, is directed to apparatus that is operative toexpeditiously reduce the time, effort and expense required to clean theinterior of tubes mounted in the tube sheets of heat exchangers.

SUMMARY OF THE INVENTION According to the present invention, therefore,there is provided apparatus operable to propel a cleaning pellet bymeans of compressed air or other motive fluid through the interior ofthe tubes assembled in the tube sheet of a heat exchanger or othersimilar apparatus. The inventive device comprises a manuallymanipulatable body forming a barrel into which pellets of absorbentmaterial such as felt or the like are individually fed from a magazine.An axially slideable ram is manually operable within the barrel forpassing the pellet from the barrel to the end of the tube selected to becleaned when the body is held in registry with a tube opening in thetube sheet. The ram contains a through-bore which communicates with thebarrel and which is connected at its opposite end to a source ofcompressed air that, when triggered, is effective to impart amotiveforce to the pellet for propelling it through the tube to wipe theinterior of the tube clean of any foreign particles or other residue.

DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevational view of a heatexchanger, partly in section, with a cleaning pellet propelling deviceaccording to the invention applied thereto;

FIG. 2 is a sectional elevational view of the cleaning pellet propellingdevice shown in FIG. 1;

FIGS. 3, 4, and 5 are partial sectional views of the body of thepropelling device illustrating diflerent positions of the ram that isoperable therein during the principal phase of operation of theapparatus.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1 of thedrawings, there is shown a device 10 constructed according to thepresent invention and illustrated in operative relation to the end ofone of a number of tubes 12 assembled in a tube sheet 14, the devicebeing operative for propelling a cleaning pellet 16 through the interiorof the tube in order to wipe the tube clean of any residue or sedimentthat may remain therein after assembly of the tube to the tube sheet.The device 10 comprises a body 18, rectangular in section, and having anaxially disposed through-bore 20 provided therein. The rear end of thebore 20 is closed by a bushing 22 which is preferably formed of brass ornylon and which has a central opening for reception of a slideable ram24 that is operative in the bore 20 as explained hereinafter.

The leading end of the bore 20 is provided with an enlarged diametersection 26 that is internally threaded for reception of a body extensionmember 28, the rear end of which is provided with a complementaryexternal thread for connection with the thread in section 26 of thebore. As shown, the extension member 28 is generally cylindrical insection with a chamfered leading end 30 that is employed to facilitatepositioning the device in registry with the end of a selected tube 12 tobe cleaned. A central bore 32 extends through the member 28 in axialalignment with the bore 20 in the body 18. The forward end of the bore32 contains an internal, converging and conically formed tapered portion34 whose function it is to compress the pellets 16 to a diameter lessthan the internal diameter of the tube in order to facilitate entranceof the pellet into the ends of the tubes 12. The smallest diameter ofthe portion 34 is less than that of the internal diameter of the tube.In being forced through the tapered portion the pellet will becompressed to a diameter to permit its ready insertion into the tube.After entering the tube end the pellet is caused to expand intoengagement with the internal tube surface due to the memorycharacteristic of the material of which it is made.

The ram 24 is manually operated and axially slideable within the bodybore 20 to advance the pellets from a load position in the bore (FIG. 3)to the tapered end 34 of the extension member 28 (FIG. 4) and thenceinto the interior of the tube 12 to be cleaned. The ram 24 comprises anaxially elongated, generally cylindrical member having a through-openingor bore 38. The rear end of the ram is threaded as at for reception of apair of axially adjustable stop nuts 42 and also to connect the numberto a tubular elbow 44 which, in turn, attaches the ram to a source ofcompressed air 46. This connection is made through a quick opening andclosing actuation valve 48 that is connected between the elbow 44- andthe compressed air source 46 by means of threaded nipples and a lengthof flexible hosing 52. The valve 48 is a normally closed valve having aspring loaded manually operated trigger 49 which is depressed to openthe valve and to place the body bore 20 in fluid communication with thecompressed air source 46.

Intermediate its ends the ram 24 is provided with an enlarged diametershoulder portion 54. The shoulder portion 54 is of limited axial extentand is cylindrically formed of a diameter having a sliding fit withinthe body bore 20 to guide the reciprocating movement of the ram withinthe body and thus prevent jamming thereof. The rear side of the shoulderportion 54 also cooperates with the bushing 22 to limit the retractedmovement of the ram, its forward movement being limited by the abutmentof the stop nuts 42 against the bushing 22.

Various seals are provided to render the device fluid tight and also toprevent rearward flow of motive fluid during the various stages of itsoperation. The seals include an O-ring 58 disposed in an internalannular groove 60 adjacent the enlarged diameter section 26 of the bodybore 20. This O-ring 58 is arranged to cooperate with the shoulderportion 54 of the ram 24 when the latter is advanced to the positionshown in FIG. 4 with the cleaning pellet disposed in the tapered portion34 of the body bore 20. Another O-ring 62 is provided adjacent theleading end of the ram 24 disposed in an annular groove 62 about theexternal surface of the ram. This seal is arranged to cooperate with theinternal diameter of the tube to be cleaned when the ram is in its fullyadvanced position, as shown in FIG. 5, to prevent the reverse flow ofmotive fluid from the tube end.

The top side of the body 18 adjacent its forward end mounts a pelletmagazine 66 formed of rectangularly arranged plate members 68 forming anelongated chamber 70 adapted to contain a plurality of cleaning pellets16. The mounting may be effected by means of securing bracket members 71attached to the magazine '66 and the body 18 on opposite sides thereofby suitable means such as threaded fasteners.

One of the plate members 70 is hingedly attached to the surface of thebody 18 by means of a pivot hinge 72 to enable the plate to be pivotallyretracted for loading the magazine chamber 70 with cleaning pellets 16.The magazine chamber 70 communicates with the bore 20 of body 18 bymeans of an opening 74 provided in the wall of the top side of the body,the latter being of such size as to permit the pellets to beindividually fed under the force of a compression spring 76 operating onplate 78 into the bore 20 when the ram 24 is retracted to its rearwardposition.

For most applications the pellets 16 employed for cleaning heat exchangetubes 12 may be formed of felt or other absorbent material. The pelletsare provided with a frusto-conical configuration and are arranged in themagazine chamber 70 with their small diameter end facing forward towardthe leading end of the device. The large diameter end of the pelletshould be of a diameter that is slightly over-sized with respect to theinternal diameter of the tubes to be cleaned. A diameter difference ofabout A; inch has been found to be adequate for most applications.

The operation of the herein-disclosed apparatus is as follows. Thedevice is manually manipulated by grasping the body 18 with one hand andthe body of the valve 48 with the other to bring the leading end of thebody extension member 28 into registry with the end of a tube 12selected to be cleaned. The chamfer 30 provided on the end of theextension member 28 assists in positioning the device. Thereafter, theram 24 is withdrawn to its retracted position as shown in FIG. 3 of thedrawing, thereby permitting one of the pellets 16 contained in themagazine chamber 70 to drop by gravity into body bore 20 immediatelyforward of the leading end of the ram 24. Thereafter, the ram is movedto its intermediate position shown in FIG. 4 to locate the pellet 16 inthe internally tapered portion 34 of the body extension member 28. Thedimensions of the tapered portion 34 are under-sized with respect to thepellet 16 such that the force generated by axial movement of the ram 24causes the pellet to be compressed by the tapered surface to an extentsufiicient to reduce the diameter of the forward end of the pellet to 4a dimension somewhat less than the internal diameter of the tube therebyfacilitating entry of the pellet into the tube. It should be noted thatwith the ram in this position, the shoulder portion 54 is in registrywith the O-ring 58 to provide an internal seal Within the bore. At thispoint, the trigger 49 of valve 48 may be actuated to admit motive fluidfrom the source 46 to the rear side of the pellet 16 in order to assistmovement of the pellet from the end of the extension member 28 into theinterior of the tube 12. Simultaneously therewith or immediatelythereafter the ram is moved forward such that its leading end togetherwith the O-ring 62 is extended into the interior of the tube 12. In thisposition the O-ring will seal the end of the tube against reverse flowof motive fluid. In order to prevent damage of the tapered surface, stopnuts 42 should be positioned on the threaded portion 40 of the ram 24 toprevent engagement of the surface 34 by the shoulder portion 54 when theram is placed in its fully extended position. Depression of the trigger49 is continued to supply motive fluid to the tube interior behind thepellet for propelling it through the tube where it wipes the interior.Fluid flow is continued until such time as the pellet 16 emerges fromthe other end of the tube 12.

By passing the pellet through the tube in this fashion the internalsurface thereof is cleaned of any sediment or liquid residue that may bedisposed therein as a result of the various steps of the fabricatingprocess. In tubes that are especially dirty, additional pellets can bepropelled through their interior by merely retracting the ram 24 to itsrearwardmost position to permit another pellet to drop into the bore 20whereupon the procedure is repeated.

It will be understood that various changes in the details, materials,and arrangements of parts which have been herein described andillustrated in order to explain the nature of the invention may be madeby those skilled in the art within the principle and scope of theinvention as expressed in the appended claims.

What is claimed is:

1. A device for propelling compressible cleaning pellets through a tubecomprising:

(a) elongated body means having a leading end adapted for registry withthe end of a tube to be cleaned,

(b) means forming a longitudinal bore through said body means andopening to the interior of said tube when said body means is in registrywith the end thereof, said bore including tapered surface means adjacentthe leading end of said body sized to compress a pellet passed throughsaid bore to a diameter less than that of said tube to facilitate entryof said pellet into said tube,

(c) a transverse pellet-receiving opening in said body meanscommunicating with said bore,

(d) a ram reciprocable in said bore from a position placing its leadingend rearwardly of said pellet-receiving opening to a position beyond theleading end of said body means, the leading end of said ram beingoperative to engage the rear end of a pellet received in said bore forpassing it through said bore and being sized to be insertable into saidtube interior for inserting said pellet therein,

(e) annular seal means externally mounted on the leading end of said ramand being sized to seal the end of said tube when said ram is in itsfully extended position,

(f) a longitudinal opening through said ram, and

(g) means for passing pellet-propelling motive fluid through saidlongitudinal opening.

2. A device as recited in claim 1 including:

(a) a bushing closing the rear end of said bore,

(b) a central opening through said bushing to guidingly receive saidram,

(0) an enlarged shoulder portion on said ram adapted to cooperate withsaid bushing to limit the rearward movement of said ram, said shoulderportion having a peripheral surface to slidingly engage the surface ofsaid bore,

((1) means on said ram forming adjustable stops longitudinally spacedfrom said shoulder portion, said stops being adapted to engage saidbushing to limit the advance movement of said ram.

3. A device as recited in claim 2 including seal means for engaging theperipheral surface of said shoulder portion when said ram is positionedto locate said pellet in registry wtih said tapered surface means.

4. A device as recited in claim 3 wherein said motive fluid passingmeans includes:

(a) a source of motive fluid,

(b) a line connecting said source and the rear end of said ram incommunication with said longitudinal opening,

(c) normally closed valve means in said line, and

(d) trigger means associated with said valve means for selectivelyopening the same for passing motive fluid through said longitudinalopening to propel said pellet through the tapered surface in said bore.

5. A device as recited in claim 1 wherein said motive fluid passingmeans includes:

(a) a source of motive fluid,

(b) a flexible line connecting said source and the rear end of said ramin communication with said longitudinal opening,

(c) normally closed valve means in said line, and

(d) trigger means associated with said valve means for selectivelyopening the same for passing motive fluid through said longitudinalopening to propel said pellet through said tube.

6. A device as recited in claim 1 including means forming a magazine forcontaining a plurality of cleaning pellets, said magazine having an openlower end communicating with said pellet receiving opening for passingindividual pellets to said bore.

References Cited UNITED STATES PATENTS I 1,715,442 6/1929 Weis 15-3.51,808,870 6/1931 Strasburg 153.5 1,814,766 7/1931 Oberhuber 15-353,011,196 12/1961 Glover 15104.06 3,147,808 9/1964 McCarvell et al.15--104.06

EDWARD L. ROBERTS, Primary Examiner

